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Fan Housing Crack Repair, epoxy or welding?

My fan housing has developed a crack that is getting worse. It is the lip around the top of the fan housing that the cooling shroud is bolted to. It is starting to separate from the rest of the fan housing, cleanly i might add. Most people recommend drilling a hole at the end of the crack, filling the crack with red epoxy, and clamping.

My idea is instead of drilling a hole, to wedge a screwdriver in the crack and hit it with a hammer to separate the lip where it's cracked from the housing, then to dremel small groves underneath the broken piece for epoxy grip, then spread epoxy on the housing and broken off piece, clamp them together, heat, and let set.

Will this hold up, or should i start looking for a certified welder that can handle magnesium? My only concern with welding the housing is that it wont fit back in place because the welding will be bumpy and wont fit under the cooling shroud.

The red epoxy method sounds great, but i plan on having the housing blasted and powder coated after, will the epoxy let go during the baking process of the powder coating?

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Last edited by dimeified; 02-10-2009 at 09:04 PM.. Reason: typo
Old 02-10-2009, 07:30 PM
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You need to have it welded by someone who knows how to work with magnesium. Becareful don't let just anyone attempt to weld it it will blow up and destroy your fan housing.

When I tried to have a magnesium welder re-weld my targa top arm, I saw bunch of explosions and he literally melt away my arm. Had to buy a replacement at the end.

Epoxy will not work due to the the high resonate and vibration will break it loose again.

Sorry I wish I had a solution because my fan housing has cracks too and I want to fix it because at times she make noise at certian frequencies.

I may just pull the trigger on a new aftermarket from Vertex.
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Last edited by DRACO A5OG; 02-10-2009 at 08:34 PM..
Old 02-10-2009, 08:31 PM
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The following link is a writeup on which i base the possibility of using red epoxy to repair a magnesium crack.
http://www.highsidechem.com/redepxy.html

If i crack off that 1 and a half inch of housing lip with a screwdriver and hammer i would think the epoxy would hold up if i glue it back on after. Red epoxy is known to hold up in high heat environments. I don't think 2 inches of cracked lip (once again referring to the lip under the cooling shroud, not the closest one to the rear of the car) is enough to be considered structural damage , considering the housing is operating fine as is. I just dont want it to get worse, and i want to blast and powder coat the housing. Although i've done my best to describe the damage, my best best is to post a pic tomorrow.
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Last edited by dimeified; 02-10-2009 at 08:43 PM..
Old 02-10-2009, 08:36 PM
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DRACO didn't say anything about an "aluminum welder." Try the epoxy first. If it works OK then good. If it doesn't you can always try a "magnesium welder." He was right. Not everyone knows how to weld magnesium. Either way, good luck.
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Old 02-10-2009, 08:44 PM
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I don't think heat is the issue but the high constant vibration/resonation. Almost like a sonic issue that will re-fracture the expoxied points.

Man, I would love it if this is the solution but I have my doubts.

I wonder if anyone has tried this?
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Old 02-10-2009, 08:47 PM
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Have it welded by a competent welder. Pay him money. The mag housing is relatively easy and very strong when done correctly. Then grind down any lumps/high spots with your dremel until the fan spins free.

I've never seen a repaired fan housing, but I've seen many a magnesium race car part welded and re-machined, including wheels. None ever failed if used properly. By properly, I mean something caused the part to crack in the first place and if there is some structural mis-alignment in the way it mounts, it will fail again in the same place, or adjacent to the old crack, until the structural mis-alignment is fixed.
Old 02-10-2009, 08:51 PM
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You could "bite the bullet" and buy a new one...

But why not try the epoxy method first. What about JB weld instead of red epoxy?

Welding Magnesium Alloy is very difficult to say the least. The fan housing has to be clamped down securely then heated to a temperature just bellow its melting point (within 10 degrees or less) and then welded by a very skilled person.

I would imagine this process being very expensive and you may have difficulty finding someone who can do it properly. (and safely)

Hope it works out OK
Old 02-10-2009, 08:53 PM
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Quote:
Originally Posted by Evans, Marv View Post
DRACO didn't say anything about an "aluminum welder." Try the epoxy first. If it works OK then good. If it doesn't you can always try a "magnesium welder." He was right. Not everyone knows how to weld magnesium. Either way, good luck.
My apologies, i thought in his reply i saw him write "aluminum welder" that was why i questioned it. After looking back, i saw it said "magnesium welder" which is why i edited my response. I am going to order some of this stuff, and this weekend i will attempt to repair this problem, hopefully with some pictures. I am not so concerned about the housing crack holding up after epoxying as much as i am worried about blasting and baking in a powder oven. Like i said, the lip under the cooling shroud is cracking off and doesn't seem too structural. With this repair, and a nice powder coat over the housing, the repair should appear undetectable to me (and only to me, i would never try to hide repairs if i ever sold the car.)
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Last edited by dimeified; 02-10-2009 at 09:00 PM..
Old 02-10-2009, 08:55 PM
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Quote:
Originally Posted by sc_rufctr View Post
You could "bite the bullet" and buy a new one...

But why not try the epoxy method first. What about JB weld instead of red epoxy?

Welding Magnesium Alloy is very difficult to say the least. The fan housing has to be clamped down securely then heated to a temperature just bellow its melting point (within 10 degrees or less) and then welded by a very skilled person.

I would imagine this process being very expensive and you may have difficulty finding someone who can do it properly. (and safely)

Hope it works out OK
I've been searching for a new one, i dont want to go with the vertex housing. Also, the rear 1-2inch lip that is slowly separating from the housing doesnt seem to be causing any scraping of the fan against the housing, so i dont think the problem is necessarily structural, and it would warrant a new housing. At least not yet anyway. My main concern is blasting and powder coating the housing after this repair.
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Last edited by dimeified; 02-10-2009 at 09:02 PM..
Old 02-10-2009, 08:57 PM
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Quote:
Originally Posted by dimeified View Post
My apologies, i thought in his reply i saw him write "aluminum welder" that was why i questioned it. After looking back, i saw it said "magnesium welder" which is why i edited my response. I am going to order some of this stuff, and this weekend i will attempt to repair this problem, hopefully with some pictures. I am not so concerned about the housing crack holding up after epoxying as much as i am worried about blasting and baking in a powder oven. Like i said, the lip under the cooling shroud is cracking off and doesn't seem too structural. With this repair, and a nice powder coat over the repair, the shroud should be good as new.
You saw correctly, I did write aluminum at first then realized my error and edited it .

Yes, please keep us posted with pics and results. I for am very interested.
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Old 02-10-2009, 09:01 PM
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I used JB weld to fill in the worn surfaces that the Targa top clips wear away. One side has held for over a year, the other popped off. On closer examination, the surface that the JB weld was adhering to, was very smooth. Roughed it up and it's holding.

It might work on the fan housing as well.
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Old 02-10-2009, 09:02 PM
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Something to note if you get your housing powdercoated. You don't want the portion where the rear of the alternator seats powdercoated. Make sure you physically show whoever powdercoats it. I sent one of mine away to have it powdercoated and they powdercoated the ledge where the alternator seats. That was after an extensive description over the phone (and they powdercoated lots of housings - they said). They apologized & said if I wanted another powdercoated, they would do it for nothing. I did have another housing, so I sent it off. They powdercoated that one wrong too.
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Old 02-10-2009, 09:09 PM
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slodave, your saying that epoxy adheres to smooth surfaces better than rough surfaces? This would mean that my "epoxy channels" that i wanted to grove into the soon to be broken off piece would not help the glue joint. I also thought that the smoother that both surfaces are, the less glue will be in the joint, and the "broken piece" would not fit flush.
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Old 02-10-2009, 09:12 PM
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glue on that is a waste of time. put a wanted ad on the 911 parts forum.
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Old 02-10-2009, 09:12 PM
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Quote:
Originally Posted by Evans, Marv View Post
Something to note if you get your housing powdercoated. You don't want the portion where the rear of the alternator seats powdercoated. Make sure you physically show whoever powdercoats it. I sent one of mine away to have it powdercoated and they powdercoated the ledge where the alternator seats. That was after an extensive description over the phone (and they powdercoated lots of housings - they said). They apologized & said if I wanted another powdercoated, they would do it for nothing. I did have another housing, so I sent it off. They powdercoated that one wrong too.
Thats a good tip, i hadn't thought of that. All the threads i read of mentioned not having the inside of the housing coated due to fan tip clearances, but i never thought of issues arriving from the alternator not seating flush against the housing, causing scraping between the fan tips and inner housing.
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Old 02-10-2009, 09:16 PM
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glue on that is a waste of time. put a wanted ad on the 911 parts forum.
Already have put a want add in there. John, if JB weld holds up repairing crank case holes/cracks why would red epoxy not hold up on a lip of a fan housing? I will really need to post pictures tomorrow when it's lighter out. The crack really doesn't seem like structural damage.
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Old 02-10-2009, 09:17 PM
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Quote:
Originally Posted by dimeified View Post
slodave, your saying that epoxy adheres to smooth surfaces better than rough surfaces? This would mean that my "epoxy channels" that i wanted to grove into the soon to be broken off piece would not help the glue joint. I also thought that the smoother that both surfaces are, the less glue will be in the joint, and the "broken piece" would not fit flush.
No, the opposite.

Anyway, just chiming in on the vibration aspect. For my application, if the surfaces are properly prepped, the jb weld seems to hold.
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Old 02-10-2009, 09:29 PM
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So i wonder if cracking off the cracked lip, wire wheeling both surfaces, and notching smooth grooves with a dremel on both surfaces would yield positive results? then at least the excess epoxy exposed outside of the crack can be wiped away since there will be epoxy resin deep inside the crack bonding the 2 pieces? I think then after epoxying, the outside surfaces of the crack will be smooth, seamless, and the powder coating will yield stellar results. I wonder if the powder coating would provide an additional layer of protection from heat or not. Definately moisture.
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Last edited by dimeified; 02-10-2009 at 09:39 PM..
Old 02-10-2009, 09:35 PM
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Quote:
Originally Posted by dimeified View Post
Thats a good tip, i hadn't thought of that. All the threads i read of mentioned not having the inside of the housing coated due to fan tip clearances, but i never thought of issues arriving from the alternator not seating flush against the housing, causing scraping between the fan tips and inner housing.
I think a lot of folks misdiagnose the fan scraping as being due to the p/c that's on the inside of the housing or the fan tips. As the other poster stated, my fan had clearance issues from the p/c that was on the lip where the altenator is secured, and only after the last turn or two of the screws that hold it in place. My powdercoater did a fantastic job (a reknowned wheel refinisher that does a lot of them) and I simply sanded the p/c off on that portion of the housing where the tolerances caused the alternator to fit ever so "slightly caddywompous". I could easily see where it's not a problem for some, and only an issue for a few. Just my personal experience...
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Old 02-11-2009, 02:32 AM
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Drilling the holes relieves the stress in the crack. It would seem to be an important step.

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